Time and time again, I have had people sending me emails asking me whether fluorescence in diamonds is a good or bad thing. Most of the time, they have heard that buying diamonds with fluorescence is recommended for lower colors and you won’t have any issues with undesirable appearances. Well, let me tell you this, the people who believe this only get half the equation correct.

Before we delve deeper into this topic, here’s an example of a diamond with an oily appearance as a result of ‘undesirable’ fluorescence.

Source: http://lgdl.gia.edu/pdfs/W97_fluoresce.pdf

There are a lot of misinformation on this topic, with many of the ‘so-called’ gurus who say that medium, strong or very strong blue fluorescence won’t cause a diamond to look milky or take up an oily appearance only in the exception of very rare cases.

And where does all these misinformation stem from? It goes all the way back to this report by GIA on a study performed with visual examinations. I strongly encourage you to download the study and read it yourself as we will be making regular references to this article. Some very contradictory statements were made and I believe many people who read the report were misled by the way the study was worded and explained.

The report itself is 16 pages long and admittedly, isn’t the most exciting paper most people would devote 1 or 2 hours of their time to. Because of this, I highly doubt that people guilty of spreading the misinformation had read through the entire study, fully understand it and thought about the results/findings in a critical manner.

Now, I come from a background in science and research where my previous job requires me to pour over statistics and read scientific journals all the time. Outside the laboratory, I am your typical geek who spends a lot of time studying and researching on specific topics. Unlike most people, I have a huge appetite for boring journals and can dissect information with the skills developed with my previous work experience.

For the record, here are the extracted sentences causing the misinformation.

Without singling out any other online resources, whenever the topic of haziness or transparency in relation to fluorescence is brought up, this GIA study would usually be quoted. Along with it usually follows bad advice that the consumer won’t have to worry about any cloudiness or undesirable appearances of a diamond with medium or strong fluorescence.

Seriously? Have They Looked at the Tabulated Findings And Results?

Let me attempt to explain the study in plain English. I am limiting my scope on the portion of fluorescence and its impact on transparency.

Basically, a group of observers from the industry (majority) and general public viewed 4 colored sets of diamonds (E, G, I, and K) with varying degrees of fluorescence under 5 different lighting conditions. They were then required to fill up a questionnaire based on their observations.

As you soon as you start to break down the results of the experiments, many unanswered questions and inconsistencies begin to surface.

If fluorescence had NO EFFECT or whatsoever on the transparency of the diamonds as claimed by GIA, why did 50% of the observers(indicated by red arrow) say that there is a perceived difference being noted?

Next, if fluorescent diamonds with milky appearances are indeed so rare, what accounted for the huge amount of observations that medium/strong/very strong fluorescence was observed to be ‘least transparent’?

I am not making this up. Verify this against the diagrams in the study yourself.

Looking at the results for experiment 3 and 4, the same questions above are raised again. Why did people report noticing differences amongst the diamonds? Surely it can’t be that many people who can spot them since it is merely a “negligible percentage of super rare diamonds” which will cause this issue.

In the last environment condition (5) that is under indirect sunlight, 50% of observers noted something going on with the diamonds when viewed beside the window in day lighting.

On first glance, you might probably wonder: “Isn’t a diamond with NO fluorescence (circled in blue) supposed to have no effects on transparency?” Why did 3 out of 24 people (12.5%) say these diamonds were the least transparent?

On the contrary, this corresponded to people who observed that strong/very strong fluorescence (circled in red) actually made the diamonds clearer than they are. Since the comparison in transparency is relative, this result comes as no surprise.

But That’s Not Saying Anything Conclusive About Fluorescence!

From this experimental finding, it might appear that fluorescence is actually helping the diamonds look transparent! What a paradox. However, the sample size is way too small for any meaningful conclusions. To put in simple words, you can ignore the findings from experiment 5 except for the fact that 50% of the observers in this test noticed differences in transparency between the diamonds. To be fair, GIA did mention that more research was needed to look into this.

Be it good or bad, the above results all seem to indicate that fluorescence has an impact on the diamonds’ appearance.

I worked as a research officer in a top government research institute in my previous job. During that time, I had penned and published several scientific papers in respectable journals. Whenever I see statistics and anomalies like this, it immediately brings the entire experiment under scrutiny.

Concrete explanations about findings are clearly lacking and nowhere to be found. In the scientific community, you will NEVER get away with contradicting results without any sound explanations in a report. This will surely cause your paper to be rejected by the reviewer.

To Put the Icing on the Cake…

Based on results that were NON-CONCLUSIVE, guess what happened in the summary?

Screw the Study, Use Your Own Eyes to Determine Cloudiness

“First, we try to impress people with nice figures and numbers that diamond fluorescence will NOT have an impact on transparency except for super rare cases.

Oh, the results are telling us a different thing? Never mind, let’s just hope no one will notice and ask questions.

Then we say that it might actually help improve transparency.

But hey, we are not sure and require more studies. Oh no… We just shot ourselves in the legs. Oh boy, what a mess… But we really need to stand by what we said earlier.

Ok, since we can’t convince them (or ourselves), let’s just try to confuse everyone.”

Damn… You Just Can’t Make Up Your Mind…

Don’t get me wrong here; the study is still valid to some extent. I can agree with the results that were shown on perceived colors of diamonds. GIA had gone to great lengths and details to explain their results and findings on that aspect.

However, when it comes to perceived transparency, things aren’t quite right there. To start off by making a claim that diamonds with undesirable fluorescence effects are SUPER RARE and contradict it later in the results doesn’t help the readers at all.

Brian Gavin’s Blues Are Handpicked

Based on my own observations of viewing diamonds physically, let me tell you that diamonds with medium – strong – very strong blue fluorescence impacting a diamond’s transparency are much more common than you think it is.

Here’s where people and even jewelers themselves get confused because they never ASK questions and simply accept what is thrown to them!

The degree of haziness doesn’t necessarily have to show itself to be as severe as the example found at the beginning of this article. Such extreme cases are what GIA termed as rare and based on the study, they only seem to consider such stones and excluded the rest with less degrees of haziness!

You see the point I am getting here? In the study that GIA conducted, 30% of the observations concluded that the transparency of the diamonds was impacted. Here’s my take, because these diamonds didn’t appear to be “super oily”, these stones were wrongly classified by the researchers to have no haziness. Gosh…

The best analogy here is eating a packet of potato chips with 80% reduced fat. Just because the chips had less fats don’t mean the chips didn’t have fats! Likewise, just because the diamonds didn’t exhibit an extreme haziness effect doesn’t mean they didn’t exhibit slight haziness effects.

Here’s My Personal Observation And Guidelines

In my opinion, it is definitely NOT SUPER RARE as claimed by GIA in their study. In fact, they published another article titled “About Fluorescence” in recent times stating that “fewer than 0.2% of the fluorescent diamonds submitted to GIA exhibit this effect”. Geez…

Generally speaking, diamonds in the colorless category D-F have a greater chance of being hazy when coupled with medium or v/strong fluorescence.

Haziness issues usually arise when we move towards a spectrum of more intense blue fluorescence. With that said, don’t be afraid of buying diamonds with strong or very strong fluorescence. The point to take note is never to buy blind. Either have a trustworthy gemologist help you review the stone or physically see the diamond before laying down your cash.

Faint fluorescence usually doesn’t impact the diamond’s look in any manner. In higher color grades like D-F, there is usually no difference in appearance. In lower color grades, faint fluorescence won’t help you much in making the stone look ‘whiter’.

On a side note, I personally love fluorescence and it is really a matter of your individual preferences when it comes to this. What you need to take back here is to exercise due caution when making a purchase. You don’t want to end up with a hazy diamond that costs you thousands of dollars.

With proper selection techniques, you can enjoy significantly lower prices. On the next page, I’ll show you how prices vary across diamonds with different fluorescence properties.

Both diamonds don’t have issues with cloudiness. Also, I think you did your research really well. Both are fantastically cut for light performance. I do think the G VVS1 diamond is the slightly better cut option between the 2.

Thanks so much for your website. I’m looking for an approximately 2 carat ring, color D-F, clarity VS1 and above, excellent cut from GIA, with a budget of $25,000 for the stone. Most of the diamonds within my budget have strong fluorescence. Will it be obvious to me from the videos/pictures if the diamond has signs of haziness? For example, I can’t see any sign of haziness in the below diamond but I’m not sure if I’m just missing it. Thanks!

From the video, fluorescence doesn’t seem to be causing an issue in haziness. To be on the safe side, I would suggest getting James Allen to eyeball the stone prior to making a purchase.

Chris-

April 11, 2017 at 3:26 am

Thanks for the information. I am looking at the following two diamonds. Any information on whether they look cloudy or any other comments you have would be helpful. I am looking for one that has very good light performance.

Thank you so much for this article! I have been doing a lot of research and there is so much conflicting information out there. I have found a diamond online that I really like but I am worried about the fluorescence, which is listed as Strong Blue. It does not look cloudy to my untrained eye but I could perhaps be missing something.

Comparing these two diamonds I know the 2 karat is a really quality but for a little more I can buy a 2.4. But my concern is the crystals and the medium flourescence on the GIA report I heard that I should avoid crystals around the table although it is a vs2 – some people reported still seeing black crystals even if it was a vs2. I also heard that better cut diamonds may actually look bigger although I don’t think it would look as big as a 2.4k.

I know we are comparing two huge differences in karat size but do u think the quality of 2.4 is worth the extra cost?

Paul Gian-

April 18, 2018 at 3:37 am

Clarity isn’t your issue. I would say that both diamonds are eyeclean. The D diamond isn’t as well cut as the G diamond. And since I prioritize cut above anything else, I do have preference for the 1st option above.

Victor-

April 28, 2018 at 12:00 pm

Hi Paul,

I’m going to a jeweler to view some strong blue fluorescent diamonds.

As a general rule, what should I be doing to assess these diamonds? Which lighting conditions would exhibit milkiness/haziness/oiliness if there was any? Should I ask to view the diamond under a blacklight to see the degree of fluorescence?

Paul Gian-

April 28, 2018 at 12:33 pm

Look at the stone in diffused lighting and if it were hazy, it shows up readily. What’s your purpose of viewing the diamond under black light and checking for intensity? It’s not as if you are going to grade it better than the professional graders who do it for a living (assuming it is a stone by GIA).

Victor-

May 1, 2018 at 1:32 pm

The question about asking to see the diamond under a blacklight is only because I’m actually quite fond of the fluorescence and would like to see how it looks when fluorescing. It’s purely to satisfy my curiosity, not to try and validate the grading.

Do jewelers normally have this kind of lighting available? Should I bring my own?

I’ve been given a lot of advice to never purchase a strong fluorescence diamond “sight unseen”. Would any haziness be evident in the HD photos provided from online diamond vendors? Would a clean looking HD photo of the diamond be sufficient inspection to purchase a strong fluorescent diamond in your opinion?

Paul Gian-

May 1, 2018 at 3:25 pm

It depends. Most jewelers should have a black light “torch” that would enable you to see the blue fluorescence being activated. It doesn’t hurt to bring your own light source.

When diamonds are hazy due to fluorescence, it’s really obvious. A video will reveal such issues easily. With the better vendors, hazy diamonds don’t even get into their inventory in the first place as they curate them for such issues. Brian Gavin is one fine example of a specialist dealing with ideal cut diamonds with blue fluorescence. You will Never see a single hazy stone in their inventory.